The formation of ice on rivers can cause discharge values to appear
unusually high. Display of these erroneous discharge data may result in
improper assessment of flow conditions and misuse of the data. For this
reason, display of discharge values for streams significantly affected
by ice may be disabled from view. Display of discharge data will resume
when ice conditions are no longer present. Discharge values for streams
minimally affected by ice will continue to be displayed. Flows for
streams with these conditions appear to increase during the night and
decrease to near-base-line conditions around midday. To estimate the
correct discharge for these streams, use the flow rate that corresponds
to the bottom of the discharge curve, rather than the peak that
corresponds to the top of the curve. Note that this method of
estimation is possible only when no surface runoff is occurring. Daily
mean discharges for periods of both significant and minimal ice-effect
will be estimated and published in the Annual Water-Data Report for the
water year in which they occurred.